Electrical heating unit.



R. KUHN & A. OAKES.

ELECTRICAL HEATING UNIT.

APPLICATION men JULY 9. 1914.

1,222,001 Patented Apr. 10, 1917.

0 0000000000 J, E,- 0000000000 l n e Z I 0000000000 51 if Q" I I I 1$151M)? Him WITNESSES: IN VEIV TORS A 56/5 A&% 72 3Q ZrcZ 2 61165 ATTORNEKS iii UNITED STATES PATENT OFFICE- BOBERT KUHN AND ARCHIE CAKES,OF DETROIT, MICHIGAN, ASSIGNORS TO FRANK KUHN, 0F DETROIT, MICHIGAN.

ELECTRICAL HEATING UNIT.

Specification of Letters Patent.

Patented Apr. 10, 1917.

Application filed July 9, 1914. Serial No. 849,939.

To all whom it may concern:

Be it known that we, ROBERT KUHN and Aroma OAnEs, citizens of the UnitedStates of America, residing at Detroit, in the county of Wayne and Stateof Michigan,- have invented certain new and useful Improvements inElectrical Heating Units, of which the following is a specification,reference being had therein to the accompanying drawings.

The invention relates to electrical heating units and more particularlyto a construction which may be used in small electrically heatedinstruments such as curling iron heaters. It is the object of theinvention to obtain a resistor of relatively high resistance. occupyingcomparatively small space, and further to so mount said resistor in acasing that the developed heat may be eliiciently used.

In the drawings:

Figure 1 is a longitudinal section;

Fig. 2 is a sectional plan View;

Fig. 3 is a cross section; and

Fig. 4 is an enlarged cross section through the reinforced insulator.

A is a suitable casing, preferably formed of sheet metal and providedwith a base section 13, an inverted U-shaped section mounted thereon andsections 1) upon opposite sides 'of the section C for completing arectangular housing. The side and top walls of this housing areapertured as indicated at D to permit the passage of air therethrough.

The electrical heating unit is mounted within the casing it anddistributes its heat by radiation tothe curling iron or other instrumentwhich may be laid on the top wall of said casing. As the amount of heatrequired is comparatively small it is necessary to have a resistor ofrelatively high resist ance and it is desirable to distribute the heatunifor-ml therefrom. This efiect is secured by forming the heating unitof an insulator strip preferably of mica, having rounded notches idistributed along its opposite sides. The resistor G is formed of a coilof wire which is looped baclr and forth over the insulator E and throughthe notches F, as shown in Fig. 2. This arrangement exposes practicallythe entire radiating surface upon the upper side of the insulator E,where the heat generated will be effective. At the same time theresistor is inclosed within the housing, which, having apertures at itsside and top, will permit the free circulation of air, therebypreventing any dangerous rise in temperature should the current be lefton when the instrument is not in use.

The ends of the resistor G are secured to clamping terminals H and I atopposite ends of the memberE, and a return connection J on one of saidterminals preferably extends to the opposite end of the strip and to aterminal post K thereof, so that the flexible conductor L may enter oneend of the in strument and be attached to both terminals. The unit ispreferably mounted upon U- shaped standards M which rise from the basewithin the space housed by the members C and D.

To impart the necessary mechanical strength and rigidity to the strip Ea metallic reinforcement N of lesser width than the strip is attached tothe underside thereof and extends longitudinally. This reinforcement maybe attached by suitable means such as rivets O which are raised to avoiddirect contact with the resistor. The reinforcement may also be furtherstrengthened by being provided with downturned flanges P upon oppositeedges thereof. Thus arcing of the insulator strip is prevented, and byreason of the fact that the reinforcement is of lesser width than theinsulator strip there will be no danger of short cirouiting theresistor.

What we claim as our invention is:-

1. An electrical heater comprising an insulator strip having notchedopposite edges, a metallic reinforcement secured to said strip andextending longitudinally on one side thereof, and a resistor looped backand forth across the opposite side of said strip from the reinforcementwith the bends of the loops engaging said notches and ex tending beneaththe portions intermediate the same.

2. An electrical heater comprising an insulator strip having a metallicreinforce-- ment of lesser width extending longitudinally on one sidethereof, the opposite edges of said strip being notched, and a resistorlooped back and forth upon the opposite side of said strip from thereinforcement with the bends of the loops extending through said notchesand beneath the' portions intermediate the same.

3. An electrical heater comprising an insulator strip having notchedopposite edges, a metallic reinforcement of lesser Width secured to saidstrip and extending longitudinally and centrally on one side thereof,and a resistor formed of a continuous coil looped back and forth acrossthe opposite side of said strip from the reinforcement With the bends ofthe loops passing through said notches and beneath the ends of theportions intermediate the same.

4. An electrical heater comprising an insulator strip having notchedopposite edges, a metallic reinforcement of lesser Width extendingcentrally and longitudinally of said strip on one side thereof, aresistor formed of a continuous coil looped back and forth across theother side of said strip from the reinforcement With the bends of theloops passing through said notches, terminals connected to one end ofsaid strip. and a returncient distance to avoid contact With the re 7sistor.

In testimony whereof We affix our signatures in presence of twoWitnesses.

RUBERT KUHN. ARCHIE UAKES. Witnesses:

HARRY W. LUYOKX, STANLEY B. OAKns.

